def main():
    E = input()
    if E[0] != "1":
        print(-1)
        return
    num_of_3 = E[1:].count("3")
    if not num_of_3 or len(E[1:]) != num_of_3:
        print(-1)
        return
    print(num_of_3)


if __name__ == "__main__":
    main()